THE ELECTRONIC-STRUCTURE OF [TE15BR4][MOOBR4](2) AND SOME GENERAL-ASPECTS OF BONDING IN CLASSICAL AND HYPERVALENT TELLURIUM HALIDES

Approximate MO and band structure calculations are used to analyze the bonding in the recently synthesized paramagnetic, semi-conducting pha se [Te15Br4][MoOBr4](2). This compound is made up of 2 types of isolat ed one-dimensional subchains: [MoOBr4](-) and [Te15Br4](2+). The [Te15 Br4](2+) chains are very similar to those in the tellurium subhalide T e2Br. The electronic structure and bonding within these chains is anal yzed and the possibility of hypervalency in both [Te15Br4][MoOBr4](2) and Te,Br is discussed. The bonding in the classically hypervalent mol ecule TeBr42- and a model Te3Br24- is compared to that of the infinite system. Our calculations indicate that both [Te15Br4][MoOBr4](2) and Te2Br contain weakly hypervalent Te atoms and that the interesting ele ctronic properties of [Te15Br4][MoOBr4](2) arise within the distinct s ublattices, which do not interact significantly.